Post-surgical thyroid ablation with low or high radioiodine activities results in similar outcomes in intermediate risk differentiated thyroid cancer patients

Radioactive iodine therapy dose impact on recurrence and survival in N1 papillary thyroid cancer

OBJECTIVE

The objective of this study is to investigate radioactive iodine therapy (RAIT) dose impact on survival and recurrence in patients with papillary thyroid cancer (PTC) with regional lymph node metastasis (N1).

METHODS

A retrospective study of PTC patients with N1 disease from 2007 to 2011 at a tertiary academic hospital collected demographics, tumor characteristics, and RAIT treatment dose. RAIT dose was stratified by total dosage less than or greater than 150 mCi. Outcomes included recurrence, immediate RAIT side-effects, and mortality.

RESULTS

A total of 60 N1a and 21 N1b patients were studied with a median follow-up of about 9 years. No statistically significant differences were found between N1a PTC patients who received high-dose vs low-dose RAIT in recurrence rate (6.9% vs 6.7%, P  > 0.999) or immediate RAIT side effects (6.9% vs 16.1%, P  = 0.426). There were no mortalities in the N1a group. For patients with N1b PTC, there were no differences between high-dose and low-dose RAIT in recurrence rate (41.7% vs 44.4%, P  > 0.999), mortality (0% vs 16.7%, P  = 0.375), or immediate RAIT side effects (8.3% vs 11.1%, P  > 0.999).

CONCLUSION

Dosages of RAIT ≥ 150 mCi do not appear to provide additional benefit in reducing recurrence compared to doses <150 mCi for N1a or N1b PTC patients. No differences in mortality or immediate RAIT side effects were observed between the two dosing regimens; however, interpretation is limited by low event rates. Large randomized trials are needed for further individualized recommendations regarding optimal RAIT dosage in N1 PTC.

Molecular Imaging and Therapy of Differentiated Thyroid Carcinoma in Adults

ABSTRACT

Differentiated thyroid carcinoma (DTC) has been increasing in incidence in the United States over the last several decades, although mortality rates have remained low. Radioactive iodine therapy (RAI-T) has been a mainstay of treatment for DTC since the 1940s. Imaging of DTC before and after RAI-T primarily focuses on molecular imaging of the sodium iodide symporter. The expanding understanding of the molecular profile of DTC has increased available treatment options. Incorporation of risk stratification to treatment approaches has led to deintensification of both surgical and nonsurgical treatments, leading to decreased morbidity without compromising disease control.

Current practice in intermediate risk differentiated thyroid cancer - a review

Although the overall prognosis for differentiated thyroid cancer (DTC) is excellent, a subset of patients will experience disease recurrence or may not respond to standard treatments. In recent years, DTC management has become more personalized in order to enhance treatment efficacy and avoid unnecessary interventions.In this context, major guidelines recommend post-surgery staging to assess the risk of disease persistence, recurrence, and mortality. Consequently, risk stratification becomes pivotal in determining the necessity of postoperative adjuvant therapy, which may include radioiodine therapy (RIT), the degree of TSH suppression, additional imaging studies, and the frequency of follow-up.However, the intermediate risk of recurrence is a highly heterogeneous category that encompasses various risk criteria, often combined, resulting in varying degrees of aggressiveness and a recurrence risk ranging from 5 to 20%. Furthermore, there is not enough long-term prognosis data for these patients. Unlike low- and high-risk DTC, the available literature is contradictory, and there is no consensus regarding adjuvant therapy.We aim to provide an overview of intermediate-risk differentiated thyroid cancer, focusing on criteria to consider when deciding on adjuvant therapy in the current context of personalized approach, including molecular analysis to enhance the accuracy of patient management.

Radioactive Iodine in Differentiated Carcinoma of Thyroid: An Overview

Thyroid cancer is the fifth most prevalent cancer in women and the fastest-growing malignancy. Although surgery is still the basis of treatment, internal radiation therapy (Brachytherapy) with radioactive iodine-131, which functions by releasing beta particles with low tissue penetration and causing DNA damage, is also a potential option. The three basic aims of RAI therapy in well-differentiated thyroid tumors are ablation of the remnant, adjuvant therapy, and disease management. Radioactive iodine dose is selected in one of two ways, empiric and dosimetric, which relies on numerous criteria. The dosage for ablation is 30-100 mCi, 30-150 mCi for adjuvant therapy, and 100-200 mCi for treatment. The RAI treatment effectively aids in the treatment to achieve complete removal of the disease and increase survival. The present review intends to emphasize the significance of radioactive iodine in the management of differentiated thyroid cancer and put forward the current breakthroughs in therapy.

Assessment of three different radioiodine doses for ablation therapy of thyroid remnants: Efficiency, complications and patient comfort

I-131 radioiodine (RAI) ablation removes postoperative residual tissue and facilitates follow-up in low- and intermediate-risk differentiated thyroid cancer (DTC). Although low doses have been reported to be as effective as higher doses for ablation, the doses administered still vary depending on the patient and the practitioner. We aimed to evaluate the ablation efficiency, complications, and length of stay (LOS) of patients with DTC treated with 3 different doses for ablation. Patients with DTC who received RAI therapy were retrospectively reviewed. One hundred thirty patients with low-intermediate-risk, according to American Thyroid Association classification, without known lymph nodes or distant metastases were included. Patients were divided into 3 groups as 30 to 50 mCi, 75 mCi, and 100 mCi. Residue thyroid and salivary glands were evaluated from 9 to 12 months post-RAI I-131 scans. No significant difference was found between groups regarding ablation success (P = .795). In multivariable analyses, pretreatment thyroglobulin (hazard ratio = 0.8, 95% confidence interval 0.601-0.952, P = .017) and anti- thyroglobulin antibody (hazard ratio = 1.0, 95% confidence interval 0.967-0.998, P = .024) were 2 independent predictors of ablation success. The mean LOS was 2.1 ± 0.3, 2.6 ± 0.6, and 2.9 ± 0.4 days, respectively, (P = .001). LOS rates of ≥ 3 days were 13.2%, 54.3%, and 84.8%, respectively. Mild decreases in hemoglobin, white blood cell (WBC), and platelet counts were observed in all groups after 6 weeks without any clinically significant findings. A lower rate of change in WBC counts was observed in the 30 to 50 mCi group compared to others. There was no dose-dependent difference regarding the early complaints questioned. Ablation with 30 to 50 mCi provides benefits such as shorter LOS, better patient comfort, less salivary gland dysfunction, and less WBC suppression, thus reducing costs without decreasing efficacy.

Establishing a Cutoff Serum Thyroglobulin Value for the Diagnosis and Management of Well-Differentiated Thyroid Cancer

Objective  The aim of this study was to define a cutoff serum thyroglobulin (Tg) level associated with either residual or metastasis that may help decide postoperative radioactive iodine (RAI) scan and treatment in differentiated thyroid cancer (DTC) patients residing in low-income countries like Nepal. Methods  We prospectively studied a total of 81 patients (female-to-male ratio of 3.0:1; mean age: 37.3 ± 14.0 years, within age range of 14-88 years) who underwent total thyroidectomy with/without neck dissection and were referred for RAI whole-body scan (WBS) ± RAI ablation or adjuvant treatment in the department of Nuclear Medicine, Chitwan Medical College. We calculated the cutoff value of Tg using receiver operating characteristic (ROC) curve analysis. Results  Forty-six of 81 patients (56.7%) had remnants in the thyroid bed, 26/81 (32.1%) had regional lymph node metastasis, 9/81 (11.1%) had distant lymph node metastasis, 3/81 (3.7%) had lung metastases, and only 1/81 (1.2%) had bone metastases. RAI WBS was positive in 61/81 (75.3%) patients and negative in 20/81 (24.7%) patients. Seventeen of 81 (20.9%) patients had negative RAI scans with low serum Tg levels; only 3/81 (3.7%) patients had Tg elevated negative RAI scan (TENIS). Although scan was positive in 61/81 (75.3%) patients, 64/81 (79.0%) patients received treatment with RAI, of which 3/81 (3.7%) patients were TENIS patients. There was a significant difference in serum Tg levels between patients who received or did not receive RAI ablation or treatment ( p  < 0.05). On ROC curve analysis, the cutoff value of Tg levels between patients who received and did not receive treatment was 2.9 ng/mL (sensitivity: 85.9%; specificity: 94.1%; positive predictive value [PPV], 98.2%; negative predictive value [NPV]: 64.0%; AUC: 0.938). Conclusion  We identified a cutoff value of 2.9 ng/mL between patients who required or did not require treatment with high sensitivity, specificity, and PPVs.

Comparison of 1.1 GBq and 2.2 GBq Activities in Patients with Low-Risk Differentiated Thyroid Cancer Requiring Postoperative 131I Administration: A Real Life Study

OBJECTIVES

To compare the efficacy of low and moderate ¹³¹I activities in low-risk differentiated thyroid carcinoma (DTC) patients requiring postoperative thyroid remnant ablation in a real-world clinical setting.

METHODS

We retrospectively reviewed the records of 299 low-risk DTC patients (pT1-T2, Nx(0) Mx) who had undergone (near)-total thyroidectomy followed by ¹³¹I therapy, using either low (1.1 GBq) or moderate (2.2 GBq) radioiodine activities. The response to initial treatments was evaluated after 8-12 months, and patient responses were classified according to the 2015 American Thyroid Association guidelines.

RESULTS

An excellent response was observed in 274/299 (91.6%) patients, specifically, in 119/139 (85.6%) and 155/160 (96.9%) patients treated with low and moderate ¹³¹I activities, respectively (p = 0.029). A biochemically indeterminate or incomplete response was observed in seventeen (22.2%) patients treated with low ¹³¹I activities and three (1.8%) patients treated with moderate ¹³¹I activities (p = 0.001). Finally, five patients showed an incomplete structural response, among which three and two received low and moderate ¹³¹I activities, respectively (p = 0.654).

CONCLUSIONS

When ¹³¹I ablation is indicated, we encourage the use of moderate instead of low activities, in order to reach an excellent response in a significantly larger proportion of patients, including patients with the unexpected persistence of the disease.

Radioiodine therapy in the different stages of differentiated thyroid cancer

Differentiated thyroid cancer is the most frequent type of thyroid cancer with an increasing incidence in the last decades. The initial management is represented by surgical treatment followed by radioactive iodine therapy that includes remnant ablation, adjuvant treatment or treatment of metastatic disease. Radioactive iodine treatment is performed only in selected cases based on the risk of recurrence and mortality during follow up, according to American Joint Committee on Cancer Union for international Cancer Control Tumor, Node, Metastasis (AJCC/TNM) staging system and the 2015 American Thyroid Association (ATA) risk stratification system. This article will review the key factors to consider when planning radioactive iodine therapy in differentiated thyroid cancer patients after surgery and during follow up.

2022 ETA Consensus Statement: What are the indications for post-surgical radioiodine therapy in differentiated thyroid cancer?

Modern use of post-operative radioactive iodine (RAI) treatment for differentiated thyroid cancer (DTC) should be implemented in line with patients' risk stratification. Although beneficial effects of radioiodine are undisputed in high-risk patients, controversy remains in intermediate-risk and some low-risk patients. Since the last consensus on post-surgical use of RAI in DTC patients, new retrospective data and results of prospective randomized trials have been published, which have allowed the development of a new European Thyroid Association (ETA) statement for the indications of post-surgical RAI therapy in DTC. Questions about which patients are candidates for RAI therapy, which activities of RAI can be used, and which modalities of pre-treatment patient preparation should be used are addressed in the present guidelines.

Outcomes after radioiodine ablation in patients with thyroid cancer: Long-term follow-up of a Chinese randomized clinicaltrial

OBJECTIVE

Two large randomized trials of patients with differentiated thyroid cancer (DTC) reported recently (HiLo and ESTIMABL1) found that the recurrence rate among patients who underwent 1.1 GBq radioactive iodine (RAI) ablation was not higher than that of patients who underwent 3.7 GBq radioactive iodine (RAI) ablation. However, no similar studies have been conducted in China. We aimed to report clinical outcomes in Chinese patients with low/intermediate risk of recurrence DTC after long-term follow-up, and evaluate the risk factors that influence the presence or absence of incomplete response at the final follow-up.

DESIGN

A long-term follow-up of a Chinese randomized clinical trial (October 2014 and February 2021) was conducted.

PATIENTS

A total of 506 DTC patients at low/intermediate risk of recurrence who were randomized into two groups to receive 1.1 (n = 251) or 3.7 GBq (n = 255) RAI ablation following thyroid hormone withdrawal were followed on levothyroxine treatment for a median of 4.5 years (range: 1.6-6.3).

MEASUREMENTS

Suppressed serum thyroglobulin (Tg) and anti-thyroglobulin antibody (TgAb) levels were determined, and neck ultrasonography was performed.

RESULTS

At the final follow-up, 499 (98.6%) patients showed an excellent response. The other seven patients (two patients underwent 1.1 GBq and five patients underwent 3.7 GBq RAI ablation, respectively) showed either structural incomplete response (lymph node metastasis, n = 1), biochemical incomplete response (increased serum Tg ≥ 1 ng/ml, or increased positive TgAb levels, n = 5), or indeterminate response (stable positive TgAb levels, n = 1). The risk of incomplete response at the final follow-up was significantly increased in patients with stimulated serum Tg ≥ 10 ng/ml at ablation (p = .003) and in patients with unsuccessful ablation (p = .008).

CONCLUSION

Our findings indicated that there was no difference in the long-term outcomes with RAI ablation using either 1.1 or 3.7 GBq in patients with low/intermediate risk of recurrence DTC, and 1.1 GBq RAI might be suitable for patients who are recommended for ablation.

Radioiodine Remnant Ablation for Differentiated Thyroid Cancer: A Systematic Review and Meta-analysis

Importance

Postoperative radioactive iodine (RAI) remnant ablation for differentiated thyroid cancer (DTC) facilitates the early detection of recurrence and represents an adjuvant therapy that targets persistent microscopic disease. The optimal activity of RAI in low- and intermediate-risk DTC remains controversial.

Objective

To evaluate the long-term cure rate of different RAI activities in low- and intermediate-risk DTC. Secondary outcomes included successful remnant ablation, adverse effects, and hospital length of stay.

Data Source

A systematic search of the databases PubMed, Cochrane Collaboration, Embase, Scopus, and Web of Science was performed to identify randomized clinical trials (RCTs) and observational studies that compared long-term outcomes (>12 months) for American Thyroid Association-classified low- and intermediate-risk DTC based on receipt of either low-activity or high-activity RAI postoperatively.

Study Selection

All RCTs or observational studies evaluating patients with low- and intermediate-risk DTC who were treated initially with total/near-total thyroidectomy, followed by remnant RAI ablation with either low or high activities. Eligible studies had to present odds ratio, relative risk (RR), or hazard ratio estimates (with 95% CIs), standard errors, or the number of events necessary to calculate these for the outcome of interest rate.

Data Extraction

Two investigators reviewed the literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Dichotomous variables were pooled as risk ratios and continuous data as weighted-mean differences. Quality assessment of the included studies was performed using the Newcastle-Ottawa and Jadad scales.

Main Outcomes and Measures

Disease recurrence was the primary outcome. Secondary outcomes included successful ablation, adverse effects, and length of stay.

Results

Ten studies that included 3821 patients met inclusion criteria, including 6 RCTs and 4 observational studies. There was no difference in long-term cure recurrence rates (RR, 0.88; 95% CI, 0.62-1.27, P = .50) or successful remnant ablation (RR, 0.95; 95% CI, 0.87-1.03; P = .20) between low-activity and high-activity RAI.

Conclusions and Relevance

In this systematic review and meta-analysis, low-activity RAI was comparable with high-activity RAI regarding successful ablation and recurrence rates. This suggests that low-activity RAI is preferable to high-activity in low- and intermediate-risk DTC because of its similar efficacy but reduced morbidity.

Trial Registration

PROSPERO Identifier: CRD42020166780.

Dosimetry during adjuvant 131I therapy in patients with differentiated thyroid cancer-clinical implications

The activity of radioiodine (¹³¹I) used in adjuvant therapy for thyroid cancer ranges between 30 mCi (1.1 GBq) and 150 mCi (5.5 GBq). Dosimetry based on Marinelli's formula, taking into consideration the absorbed dose in the postoperative tumour bed (D) should systematise the determination of ¹³¹I activity. Retrospective analysis of 57 patients with differentiated thyroid cancer (DTC) after thyreidectomy and adjuvant ¹³¹I therapy with the fixed activity of 3.7 GBq. In order to calculate D from Marinelli's formula, the authors took into account, among other things, repeated dosimetry measurements (after 6, 24, and 72 h) made during scintigraphy and after administration of the therapeutic activity or radioiodine. In 75% of the patients, the values of D were > 300 Gy (i.e. above the value recommended by current guidelines). In just 16% of the patients, the obtained values fell between 250 and 300 Gy, whereas in 9% of the patients, the value of D was < 250 Gy. The therapy was successful for all the patients (stimulated Tg < 1 ng/ml and ¹³¹I uptake < 0.1% in the thyroid bed in follow-up examination). Dosimetry during adjuvant ¹³¹I therapy makes it possible to diversify the therapeutic activities of ¹³¹I in order to obtain a uniform value of D.

Change in Practice of Radioactive Iodine Administration in Differentiated Thyroid Cancer: A Single-Centre Experience

OBJECTIVE

Our study aimed to analyse temporal trends in radioactive iodine (RAI) treatment for thyroid cancer over the past decade; to analyse key factors associated with clinical decisions in RAI dosing; and to confirm lower activities of RAI for low-risk patients were not associated with an increased risk of recurrence.

METHODS

Retrospective analysis of 1,323 patients who received RAI at a quaternary centre in Australia between 2008 and 2018 was performed. Prospectively collected data included age, gender, histology, and American Joint Committee on Cancer stage (7th ed). American Thyroid Association risk was calculated retrospectively.

RESULTS

The median activities of RAI administered to low-risk patients decreased from 3.85 GBq (104 mCi) in 2008-2016 to 2.0 GBq (54 mCi) in 2017-2018. The principal driver of this change was an increased use of 1 GBq (27 mCi) from 1.3% of prescriptions in 2008-2011 to 18.5% in 2017-2018. In patients assigned as low risk per ATA stratification, lower activities of 1 GBq or 2 GBq (27 mCi or 54 mCi) were not associated with an increased risk of recurrence. In patients assigned to intermediate- or high-risk categories who received RAI as adjuvant therapy, there was no difference in risk of recurrence between 4 GBq (108 mCi) and 6 GBq (162 mCi).

CONCLUSIONS

Our data demonstrate an evolution of RAI activities consistent with translation of ATA guidelines into clinical practice. Use of lower RAI activities was not associated with an increase in recurrence in low-risk thyroid cancer patients. Our data also suggest lower RAI activities may be as efficacious for adjuvant therapy in intermediate- and high-risk patients.

Intermediate-risk thyroid carcinoma: indicators of a poor prognosis

OBJECTIVE

The intermediate-risk (IR) category includes tumors with different degrees of aggression. We aimed to identify the risk factors associated with unfavorable response to initial treatment and compare the effect of low/high radioactive iodine (RAI) therapy.

METHODS

A total of 614 IR patients were selected from a database, during 1972-2015. All patients underwent total thyroidectomy and RAI therapy and were reclassified after 12-18 months into the favorable (complete/indeterminate) response group and the unfavorable (biochemical/incomplete structural) response group. A total of 92 patients were assessed for late response (mean: 9.19 ± 5.73 years). Age, gender, tumor size, histology, multifocality, vascular invasion, extrathyroidal extension, presence and number of lymph node metastasis, and stimulated thyroglobulin at ablation (sTg) were evaluated.

RESULTS

Mean age at diagnosis was 41.47 ± 15.81 years, and 83.6% of the patients were female. Within 12-18 months after initial therapy, unfavorable response was detected in 41.2% of the patients and was associated, in multivariate analysis, with lymph node metastasis (p = 0.041; odds ratio [OR] = 1.9), presence of more than five metastatic lymph nodes (p = 0,017; OR = 2.6), and sTg > 10 ng/mL (p = 0.005; OR = 10.0). For patients with a longer follow-up, sTg >10 ng/mL was associated with unfavorable response (p = 0.002; OR = 6.8). A higher RAI dose was not related to better prognosis at the end of the follow-up.

CONCLUSION

A sTg level of >10 ng/mL and lymph node metastasis were associated with an unfavorable response 12-18 months after initial treatment. A RAI dose below 150 mCi was proven sufficient to treat IR patients.

Radioiodine in Differentiated Thyroid Carcinoma: Do We Need Diagnostic Pre-Ablation Iodine-123 Scintigraphy to Optimize Treatment?

Changing insights regarding radioiodine (I-131) administration in differentiated thyroid carcinoma (DTC) stir up discussions on the utility of pre-ablation diagnostic scintigraphy (DxWBS). Our retrospective study qualitatively and semi-quantitatively assessed posttherapy I-131 whole-body scintigraphy (TxWBS) data for thyroid remnant size and metastasis. Findings were associated with initial treatment success after nine months, as well as clinical, histopathological, and surgical parameters. Possible management changes were addressed. A thyroid remnant was reported in 89 of 97 (92%) patients, suspicion of lymph node metastasis in 26 (27%) and distant metastasis in 6 (6%). Surgery with oncological intent and surgery by two dedicated thyroid surgeons were independently associated with a smaller remnant. Surgery at a community hospital, aggressive tumor histopathology, histopathological lymph node metastasis (pN1) and suspicion of new lymph node metastasis on TxWBS were independently associated with an unsuccessful treatment. Thyroid remnant size was unrelated to treatment success. All 13 pN1 patients with suspected in situ lymph node metastases on TxWBS had an unsuccessful treatment, opposite 19/31 (61%) pN1 patients without (p = 0.009). Pre-ablative knowledge of these TxWBS findings had likely influenced management in 48 (50%) patients. Additional pre-ablative diagnostics could optimize patient-tailored I-131 administration. DxWBS should be considered, especially in patients with pN1 stage or suspected in situ lymph node metastasis. Dependent on local surgical expertise, DxWBS is not recommended to evaluate thyroid remnant size.

Long-Term Oncological Outcome Comparison between Intermediate- and High-Dose Radioactive Iodine Ablation in Patients with Differentiated Thyroid Carcinoma: A Propensity Score Matching Study

BACKGROUND

Radioactive iodine (RAI) ablation is recommended for most patients with differentiated thyroid carcinoma (DTC) after total thyroidectomy (TT). We aimed to compare long-term outcomes between intermediate-dose (100 mCi) and high-dose (150 mCi) RAI ablation therapy in patients with DTC using propensity score matching analysis.

METHODS

This was a retrospective study of 1448 patients with DTC who underwent RAI ablation after TT. Propensity score matching was performed using the extent of operation, tumor size, extrathyroidal extension, multifocality, lymphatic invasion, vascular invasion, perineural invasion, number of positive lymph nodes (LNs), ATA risk stratification system, T stage, N stage, TNM stage, preoperative serum Tg and TgAb levels, and post-RAI serum Tg and TgAb levels.

RESULTS

Recurrence rates in the intermediate- and high-dose groups were 3.1% and 5.6%, respectively. After propensity score matching, LN ratio >0.22 (HR, 2.915; 95% CI, 1.228-6.918; p=0.015) and serum Tg >10 ng/mL after RAI (HR, 3.976; 95% CI, 1.839-8.595; p < 0.001) were significant predictors of recurrence. Kaplan-Meier analysis showed no significant difference in DFS before or after propensity score matching (p=0.074 and p=0.378, respectively).

CONCLUSIONS

Intermediate-dose RAI ablation for the adjuvant treatment of DTC is sufficient as compared to high-dose RAI ablation. Further prospective or multicenter studies should be conducted to clarify the prognosis of intermediate-dose RAI ablation.

Personalized treatment for differentiated thyroid cancer: current data and new perspectives

More conservative and personalized treatment options have been developed in recent years to face the rising diagnosis of low-risk differentiated thyroid carcinoma (DTC). The present review describes the change towards a more risk-adapted management either in the treatment or in the follow-up of DTC. Particular attention is given to the innovations introduced by the latest guidelines for low-risk tumors, starting from the most appropriate extension of surgery up to the postoperative management. The emerging role of active surveillance for low-risk microcarcinoma is discussed, as well as the development of percutaneous strategies in the setting of malignant thyroid disease. The recent use of approved new systemic target therapies for advanced radioiodine refractory thyroid cancer is reported, together with the description of new compounds in trial. Finally, we provide some considerations to improve the risk evaluation in a presurgical setting, especially related to the rising role of genetics, to enable better risk-based cancer management and personalized treatment choices.

Preoperative Use of Intravenous Contrast Media Is Associated With Decreased Excellent Response Rates in Intermediate-Risk DTC Patients Who Subsequently Receive Total Thyroidectomy and Low-Dose RAI Therapy

Purpose: To evaluate the impact of preoperative use of intravenous contrast media (ICM) on the excellent response (ER) rates in a cohort of intermediate-risk differentiated thyroid cancer (DTC) patients who received total thyroidectomy (TT) and low-dose radioactive iodine (RAI) therapy.

Methods: A total of 683 consecutive patients were retrospectively reviewed in a single center between August 2016 and August 2018. Patients were divided into ICM group (n = 532) and non-ICM group (n = 151). Intravenous contrast media patients were 1:1 propensity matched to non-ICM patients based on T stage, N stage, and urinary iodine. Risk-adjusted logistic regression models were constructed to assess the association between the use of ICM and ER rates.

Results: Intravenous contrast media patients had significantly higher T stage (P < 0.001), N stage (P < 0.001), urinary iodine (P < 0.001), and ps-Tg (P = 0.042) than non-ICM patients. Preoperative use of ICM was found to be significantly associated with decreased ER rates in both the primary cohort [odds ratio (OR) = 0.47, 95% confidence interval (CI) = 0.32–0.71; P < 0.001] and the matched cohort (OR = 0.48, 95% CI = 0.25–0.94; P = 0.031). Subgroup analysis on RAI delay time in the primary cohort revealed that ER rates in ICM patients were significantly lower than that of non-ICM patients for 1–2 months (P = 0.0245) and >2–3 months (P = 0.0221) subgroups, but not for >3–4 months, >4–5 months, and >5–6 months subgroups (all P > 0.05). A delay time of >3–4 months exhibited the highest ER rate (63.08%) within the ICM group.

Conclusions: Preoperative use of ICM is associated with decreased ER rates in intermediate-risk DTC patients who subsequently receive TT and low-dose RAI therapy. For such patients, if ICM has already been received, an RAI delay time of >3–4 months would seem to be more appropriate to achieve better ER rates.

Randomised comparison of 1.1 GBq and 3.7 GBq radioiodine to ablate the thyroid in the treatment of low-risk thyroid cancer: a 13-year follow-up

Purpose: The optimal activity of radioiodine (I-131) administered for ablation therapy in papillary and follicular thyroid cancer after thyroidectomy remains unknown in a long-term (> 10 year) follow-up. Some, shorter follow-up studies suggest that activities 1.1 GBq and 3.7 GBq are equally effective. We evaluated the long-term outcomes after radioiodine treatment to extend current knowledge about the optimal ablative dose of I-131.Methods: One hundred and sixty consecutive adult patients (129 females, 31 males; mean age 46 ± 14 y, range 18-89 y) diagnosed with histologically confirmed differentiated thyroid cancer, were randomised in a prospective, phase III, open-label, single-centre study, to receive either 1.1 GBq or 3.7 GBq of I-131 after thyroidectomy. At randomisation, patients were stratified according to the histologically verified cervical lymph node status and were prepared for ablation using thyroid hormone withdrawal. No uptake in the whole-body scan with I-131 and serum thyroglobulin concentration less than 1 ng/mL at 4-8 months after treatment was considered successful ablation.Results: Median follow-up time was 13.0 years (mean 11.0 ± 4.8 y; range 0.3-17.1 y). Altogether 81 patients received 1.1 GBq with successful ablation in 45 (56%) patients. In the original study, thirty-six patients (44%) needed one or more extra administrations to replete the ablation. Of these, 4 (8.9%) and 5 (14%) patients relapsed during the follow-up, respectively. Of the 79 patients treated with 3.7 GBq 45 (57%) had successful ablation after one administration of radioiodine and 34 (43%) needed several treatments. Of these, 2 (4.4%) and 9 (26.5%) patients relapsed, respectively. The groups did not differ in the proportion of patients relapsing (p = .591).Conclusion: During follow-up of median 13 years, 3.7 GBq is not superior to 1.1 GBq in the radioiodine treatment after thyroidectomy in papillary and follicular thyroid cancer.

Clinical Outcomes of N1b Papillary Thyroid Cancer Patients Treated with Two Different Doses of Radioiodine Ablation Therapy

BACKGROUND

The optimal dose of radioactive iodine (RAI) therapy for N1b papillary thyroid carcinoma (PTC) is controversial. We evaluated the clinical outcome of N1b PTC patients treated with either 100 or 150 mCi of RAI.

METHODS

We retrospectively analyzed N1b PTC patients who underwent total thyroidectomy and postoperative RAI therapy at a tertiary referral center between 2012 and 2017. As the baseline characteristics differed between treatment groups, we performed exact matching for various pathological factors according to RAI dose. We evaluated the response to therapy and recurrence-free survival (RFS) in the matched patients. Structural recurrent/persistent disease was defined as new structural disease detected after initial therapy, which was confirmed by cytology or pathology.

RESULTS

Of the total 436 patients, 37 (8.5%) received 100 mCi of RAI and 399 (91.5%) received 150 mCi of RAI. After an exact 1:3 matching, 34 patients in the 100 mCi group and 100 patients in the 150 mCi group remained. There was no significant difference in response to therapy between the groups in the matched population (P=0.63). An excellent response was achieved in 70.6% (n=24) of patients in the 100 mCi group and 76.0% (n=76) in the 150 mCi group. Two (5.9%) patients in the 100 mCi group and four (4.0%) in the 150 mCi group had recurrence and there was no significant difference in RFS between the groups in the matched population (P=0.351).

CONCLUSION

There were no differences in response to therapy and RFS in N1b PTC patients according to RAI dose.

Assessment of the impact of 2015 American Thyroid Association guidelines in management of differentiated thyroid cancer patients

The 2015 American Thyroid Association (ATA) guideline have suggested modifications in the risk stratification (RS) for differentiated thyroid cancer (DTC) patients, introduced the concept of dynamic risk stratification (DRS) and redefined the role of radioactive iodine (RAI) in treatment algorithm. The aim of this retrospective audit was to assess the practical implications of these modifications in management of DTC.

METHODS

A total of 138 DTC patients were stratified according to ATA 2009 and 2015 guidelines into low (LR), intermediate (IR) and high (HR) risk groups. Change in RS and in intention of RAI use was calculated. Deviation in administered RAI dosage from the guidelines was assessed. 1-year follow-up data was audited to assess how the DRS modified the initial risk estimate.

RESULTS

A total of 11.6% of patients changed their RS categories in 2015 guidelines. A total of 10.1% got upstaged to HR, and 1.4% got downstaged to LR. In 2.17% of patients' intention of RAI use changed to remnant ablation from adjuvant therapy and 65% of the LR patients won't require any RAI therapy. A total of 26.7% of patients had received significantly more RAI dosage according to ATA 2015. At 1-year follow-up according to DRS 84% of LR, 75% of IR and 44% of HR patients showed excellent response (ER).

CONCLUSION

More patients changed RS to HR than to LR. Intention of RAI use changed in only a small number of patients. Significantly higher dosage of RAI is being administered to patients in current practice. The effect of DRS in modifying the initial RS was most prominent in IR, with most showing ER to initial therapy.

Comparison between the different doses of radioactive iodine ablation prescribed in patients with intermediate-to-high-risk differentiated thyroid cancer

OBJECTIVE

This study aimed to compare the clinical outcomes of patients who received radioactive iodine (RAI) ablation after undergoing thyroidectomy for intermediate-to-high-risk differentiated thyroid carcinoma (DTC) according to the American Thyroid Association (ATA) criteria.

METHODS

We retrospectively examined patients who underwent RAI ablation for DTC after surgical resection without macroscopic residual lesions or metastatic lesions between December 2011 and August 2016. Among 147 patients who underwent RAI ablation, those whose initial pathological stages or RAI ablation results were unknown and whose distant metastases were confirmed during RAI ablation were excluded. Low-dose therapy was defined as administration of 1110 MBq of ¹³¹iodine (¹³¹I), while high-dose therapy referred to administration of 2960-3700 MBq of ¹³¹I. We defined initial success of RAI ablation as a serum thyroglobulin concentration of < 2.0 ng/mL without thyroid-stimulating hormone stimulation and disappearance of ¹³¹I uptake in the thyroid bed on ¹³¹I scintigraphy 6-12 months after RAI ablation. RAI ablation success rates were compared between the low-dose and high-dose groups using Fisher's exact test, and inverse probability of treatment weighting (IPTW) analysis was performed for adjusting potential biases.

RESULTS

Among the 119 patients examined in this study (39 men and 80 women), 79 were classified as having intermediate risk, while 40 were classified as having high risk based on the ATA guideline. Initial RAI ablation success was achieved in 50/68 (73.5%) patients from the low-dose group and in 36/51 patients (70.6%) from the high-dose group (p = 0.84). Moreover, IPTW analysis showed no significant difference between the low-dose and high-dose groups. However, the success rate tended to be superior in high-risk patients who received high-dose therapy (86.2%) than in those who received low-dose therapy (72.7%) (p = 0.37).

CONCLUSION

There was no significant difference in the RAI ablation success rate between the low-dose and high-dose groups involving patients with intermediate-to-high-risk DTC. However, high-dose RAI ablation may be recommended in high-risk patients.

Recombinant Thyrotropin vs Levothyroxine Withdrawal in 131I Therapy of N1 Thyroid Cancer: A Large Matched Cohort Study (ThyrNod)

CONTEXT

Recombinant human thyrotropin (rhTSH) has been shown to be an effective stimulation method for radioactive iodine (RAI) therapy in differentiated thyroid cancer, including in those with nodal metastases (N1 DTC).

OBJECTIVES

To demonstrate the noninferiority of rhTSH vs thyroid hormone withdrawal (THW) in preparation to RAI regarding disease status at the first evaluation in the real-life setting in patients with N1 DTC.

DESIGN

This was a French multicenter retrospective study. Groups were matched according to age (<45/≥45 years), number of N1 nodes (≤5/>5 lymph nodes), and stage (pT1-T2/pT3).

RESULTS

The cohort consisted of 404 patients pT1-T3/N1/M0 DTC treated with rhTSH (n = 205) or THW (n = 199). Pathological characteristics and initially administrated RAI activities (3.27 ± 1.00 GBq) were similar between the two groups. At first evaluation (6 to 18 months post-RAI), disease-free status was defined by thyroglobulin levels below threshold and a normal ultrasound. Disease-free rate was not inferior in the rhTSH group (75.1%) compared with the THW group (71.9%). The observed difference between the success rates was 3.3% (-6.6 to 13.0); rhTSH was therefore considered noninferior to THW because the upper limit of this interval was <15%. At the last evaluation (29.7 ± 20.7 months for rhTSH; 36.7 ± 23.8 months for THW), 83.5% (rhTSH) and 81.5% (THW) of patients achieved a complete response. This result was not influenced by any of the known prognostic factors.

CONCLUSIONS

A preparation for initial RAI treatment with rhTSH was noninferior to that with THW in our series of pT1-T3/N1/M0-DTC on disease-free status outcomes at the first evaluation and after 3 years.

Conventional Radioiodine Therapy for Differentiated Thyroid Cancer

This article presents an overview of the use of radioactive iodine (131-I) in the treatment of patients with differentiated thyroid cancer. Topics reviewed include definitions; staging; the 2 principal methods for selection of 131-I dosage; the indications for ablation, adjuvant treatment, and treatment; the recommendations for the use of 131-I contained in the guidelines of the American Thyroid Association and the Society of Nuclear Medicine and Molecular Imaging; the dosage recommendations and selection of dosage approach for 131-I by these organizations; the use of recombinant human thyrotropin for radioiodine ablation, adjuvant therapy, or treatment; and the MedStar Washington Hospital Center approach.

Radioiodine treatment of differentiated thyroid cancer related to guidelines and scientific literature

In differentiated thyroid cancer (DTC), radioiodine is administered to eliminate residual normal thyroid tissue after thyroidectomy (ablative treatment), to treat residual microscopic disease (adjuvant treatment), and to treat macroscopic or metastatic disease. Currently, treatment of DTC with ¹³¹I is still a matter of controversy due to the absence of prospective clinical trials assessing its benefit in terms of overall survival and recurrence-free interval. The current recommendations of the experts are based on observational retrospective data and on their interpretation of the literature. Pending the results of the prospective trials that are currently underway, the use of ¹³¹I seems to be justified not only in high-risk patients, but also in intermediate-risk and low-risk patients. The guidelines of The American and British Thyroid Association, European and American Societies of Nuclear Medicine, The European Consensus Group and the latest edition of National Comprehensive Cancer Network (NCCN) were considered in drawing up this continuing education document, we also undertook a review of the related scientific literature.

High-Dose RAI Therapy Justified by Pathological N1a Disease Revealed by Prophylactic Central Neck Dissection for cN0 Papillary Thyroid Cancer Patients: Is it Superior to Low-Dose RAI Therapy?

OBJECTIVE

One of the presumed advantages of prophylactic central neck dissection (pCND) is offering staging basis for more aggressive radioactive iodine (RAI) therapy, which postulates the necessity of high dose for treatment efficacy. The present study aims to compare the effectiveness between low-dose and high-dose RAI in a select cohort of cN0 papillary thyroid cancer (PTC) patients with pathological N1a (pN1a) disease revealed by pCND in terms of ablation rate and response to therapy. The frequency of short-term adverse effects between the two groups was also compared.

PATIENTS AND METHODS

From January 2014 to April 2016, cN0 PTC patients with pN1a disease revealed by pCND in our hospital were retrospectively reviewed. Patients with other indications for high-dose RAI, such as the presence of extrathyroidal extension, vascular invasion or suspicions of distant metastasis, were excluded. For the included patients, high dose (3700 MBq) was administered between January 2014 and August 2015 and low dose (1110 MBq) between August 2015 and April 2016. Ablation assessment was performed 6 months after RAI therapy. Response evaluation after RAI therapy was performed after 46.3 ± 9.5 months for high-dose group and 29.1 ± 2.6 months for low-dose group. All patients were also evaluated for short-term adverse effects 24 and 72 hours after RAI administration.

RESULTS

A total of 84 patients were enrolled. Among them, 42 were in the high-dose group and the other 42 in the low-dose group. There was no significant difference in ablation rate (P = 0.7707) and response to RAI therapy (P = 0.6454) between the two groups. Twenty-four hours after RAI administration, neck pain and swelling (33.3% VS. 11.9%; P = 0.0372) and gastrointestinal discomfort (45.2% vs. 21.4%; P = 0.0373) were significantly more frequent in the high-dose group.

CONCLUSION

High-dose RAI therapy, with higher frequency of short-term adverse effects, appears to be not superior to low-dose RAI therapy for cN0 PTC patients with pN1a disease revealed by pCND to achieve better response to therapy. Further randomized studies with larger series of patients and longer follow-up duration, especially with the low-dose group, are needed to validate our results.

Recurrence after low-dose radioiodine ablation and recombinant human thyroid-stimulating hormone for differentiated thyroid cancer (HiLo): long-term results of an open-label, non-inferiority randomised controlled trial

BACKGROUND

Two large randomised trials of patients with well-differentiated thyroid cancer reported in 2012 (HiLo and ESTIMABL1) found similar post-ablation success rates at 6-9 months between a low administered radioactive iodine (¹³¹I) dose (1·1 GBq) and the standard high dose (3·7 GBq). However, recurrence rates following radioactive iodine ablation have previously only been reported in observational studies, and recently in ESTIMABL1. We aimed to compare recurrence rates between radioactive iodine doses in HiLo.

METHODS

HiLo was a non-inferiority, parallel, open-label, randomised controlled factorial trial done at 29 centres in the UK. Eligible patients were aged 16-80 years with histological confirmation of differentiated thyroid cancer requiring radioactive iodine ablation (performance status 0-2, tumour stage T1-T3 with the possibility of lymph-node involvement but no distant metastasis and no microscopic residual disease, and one-stage or two-stage total thyroidectomy). Patients were randomly assigned (1:1:1:1) to 1·1 GBq or 3·7 GBq ablation, each prepared with either recombinant human thyroid-stimulating hormone (rhTSH) or thyroid hormone withdrawal. Patients were followed up at annual clinic visits. Recurrences were diagnosed at each hospital with a combination of established methods according to national standards. We used Kaplan-Meier curves and hazard ratios (HRs) for time to first recurrence, which was a pre-planned secondary outcome. This trial is registered with ClinicalTrials.gov, number NCT00415233.

RESULTS

Between Jan 16, 2007, and July 1, 2010, 438 patients were randomly assigned. At the end of the follow-up period in Dec 31, 2017, median follow-up was 6·5 years (IQR 4·5-7·6) in 434 patients (217 in the low-dose group and 217 in the high-dose group). Confirmed recurrences were seen in 21 patients: 11 who had 1·1 GBq ablation and ten who had 3·7 GBq ablation. Four of these (two in each group) were considered to be persistent disease. Cumulative recurrence rates were similar between low-dose and high-dose radioactive iodine groups (3 years, 1·5% vs 2·1%; 5 years, 2·1% vs 2·7%; and 7 years, 5·9% vs 7·3%; HR 1·10 [95% CI 0·47-2·59]; p=0·83). No material difference in risk was seen for T3 or N1 disease. Recurrence rates were also similar among patients who were prepared for ablation with rhTSH and those prepared with thyroid hormone withdrawal (3 years, 1·5% vs 2·1%; 5 years, 2·1% vs 2·7%; and 7 years, 8·3% vs 5·0%; HR 1·62 [95% CI 0·67-3·91]; p=0·28). Data on adverse events were not collected during follow-up.

INTERPRETATION

The recurrence rate among patients who had 1·1 GBq radioactive iodine ablation was not higher than that for 3·7 GBq, consistent with data from large, recent observational studies. These findings provide further evidence in favour of using low-dose radioactive iodine for treatment of patients with low-risk differentiated thyroid cancer. Our data also indicate that recurrence risk was not affected by use of rhTSH.

FUNDING

Cancer Research UK.

Papillary Thyroid Micro Carcinoma: The Incidence of High-Risk Features and Its Prognostic Implications

Background: The current management of papillary thyroid micro carcinoma (PTMC) has become more conservative. However, high-risk characteristics that can only be revealed post-surgically exist. Patients and clinicians need to estimate the risks and understand the prognostic meaning of these factors. Methods: We retrospectively analyzed 246 consecutive patients with PTMC who underwent surgery at our institution between 2015 and 2017. Clinical and histopathological parameters that may indicate recurrent disease were investigated. The responses to therapy in cases with different risks of recurrence were analyzed. Results: A total of 79.26% (195/246) of patients received total thyroidectomy (TT), of whom 177 (90.77%) also received central lymph node dissection. Radioiodine ablation (RAI) was applied in 64.23% (158/246) of patients. Intermediate-high risk features were identified in 27.64% (68/246) after primary treatment. After a median follow-up of 18 months (range, 6-39 months), 121 of 158 (76.58%) patients who received TT+RAI were evaluated as an excellent response. An incomplete response (IR) was observed in 14.56% (23/158) of this group of PTMC. Multivariate analysis identified extra thyroid extension (P = 0.001) and intermediate-high risk stratification (P = 0.014) as significant and independent risk factors for an IR. Conclusions: A total of 27.64% of PTMC cases evaluated as a low risk of recurrence pre-surgery showed intermediate to high risk disease post-surgery, and this leads to a higher rate of IR.

Differentiated Thyroid Cancer, From Active Surveillance to Advanced Therapy: Toward a Personalized Medicine

Differentiated thyroid cancer (DTC) is the most frequent endocrine malignancy and represents the most rapidly increasing cancer diagnosis worldwide. In the last 20 years, this increase has been mostly due to a higher detection of small papillary thyroid cancers, with doubtful effects on patients' outcome. In fact, despite this growth, cancer-related death remained stable over the years. The growing detection of microcarcinomas associated to the indolent behavior of these cancers led to the development of strategies of active surveillance in selected centers of different countries. Moreover, toward a more personalized approach in the management of DTC patients, surgical treatments became more conservative, favoring less extensive options in patients at low risk of recurrence. The rise in lobectomy in low-risk cases and the need to avoid further therapies, with controversial impact on recurrences and cancer-related death in selected intermediate risk cases, led to reconsider the use of radioiodine treatment, too. Since clinicians aim to treat different patients with different modalities, the cornerstone of DTC follow-up (i.e., thyroglobulin, thyroglobulin autoantibodies, and neck ultrasound) should be interpreted consistently with this change of paradigm. The introduction of novel molecular target therapies (i.e., tyrosine kinase inhibitors), as well as a better understanding of the mechanisms of immune checkpoint inhibitor therapies, is radically changing the management of patients with advanced DTC, in whom no treatment option was available. The aim of this review is to analyze the most recent developments of the management of DTC, focusing on several key issues: active surveillance strategies, initial treatment, dynamic risk re-stratification, and therapeutic options in advanced DTC.

THYROGLOBULIN AS A TUMOR MARKER IN DIFFERENTIATED THYROID CANCER - CLINICAL CONSIDERATIONS

SUMMARY – Initial treatment of the majority of patients with differentiated thyroid cancer (DTC) includes total thyroidectomy. Postoperative ablation therapy with radioactive iodine (I-131) is indicated in all high-risk patients, however, there is disagreement regarding its use in low- and intermediate-risk patients. Over the last few decades, thyroglobulin (Tg) has been established as the primary biochemical tumor marker for patients with DTC. Thyroglobulin can be measured during thyroid hormone therapy or after thyroid-stimulating hormone (TSH) stimulation, through thyroid hormone withdrawal or the use of human recombinant TSH. In many studies, the cut-off value for adequate Tg stimulation is a TSH value ≥30 mIU/L. However, there is an emerging body of evidence suggesting that this long-established standard should be re-evaluated, bringing this threshold into question. Recently, a risk stratification system of response to initial therapy (with four categories) has been introduced and Tg measurement is one of the main components. The relationship between the Tg/TSH ratio and the outcome of radioiodine ablation has also been studied, as well as clinical significance of serum thyroglobulin doubling-time. The postoperative serum Tg value is an important prognostic factor that is used to guide clinical management, and it is the most valuable tool in long term follow-up of patients with DTC.

Thyroid Cancer Radiotheragnostics: the case for activity adjusted 131I therapy

Radiotheragnostics represents the systematic integration of diagnostic imaging and therapeutics using radionuclides targeting specific characteristics of tumor biology. Radioiodine (¹³¹I) is the classic radiotheragnostic agent used for the diagnosis and treatment of differentiated thyroid cancer (DTC) based on sodium-iodine symporter expression in normal and neoplastic thyroid tissue. Application of radiotheragnostics principles in thyroid cancer involves using pre-ablation diagnostic scans (Dx Scans) for detection of iodine-avid regional and distant metastatic disease and patient-individualized targeted ¹³¹I therapy with goal of maximizing the benefits of the first therapeutic ¹³¹I administration. Clinically available nuclear medicine imaging technology has significantly evolved over the past 10 years with the introduction of hybrid SPECT/CT and PET/CT systems, as well as advances in iterative image reconstruction with modeling of image degrading physical factors. This progress makes possible the acquisition of accurate diagnostic radioiodine scintigraphy capable of identifying regional and distant metastatic disease, which can be used for ¹³¹I treatment planning and delivery of activity adjusted ¹³¹I therapy for achieving intended treatment goals (e.g. remnant ablation, adjuvant ¹³¹ I treatment and targeted 131-I treatment). The overarching aim of thyroid cancer radiotheragnostics is to optimize the balance between ¹³¹I therapeutic efficacy and potential side-effects on non-target tissues.

Italian consensus on diagnosis and treatment of differentiated thyroid cancer: joint statements of six Italian societies

BACKGROUND

Thyroid nodules are a common clinical problem, and differentiated thyroid cancer is becoming increasingly prevalent.

METHODS

Six scientific Italian societies entitled to cure thyroid cancer patients (the Italian Thyroid Association, the Medical Endocrinology Association, the Italian Society of Endocrinology, the Italian Association of Nuclear Medicine and Molecular Imaging, the Italian Society of Unified Endocrine Surgery and the Italian Society of Anatomic Pathology and Diagnostic Cytology) felt the need to develop a consensus report based on significant scientific advances occurred in the field.

OBJECTIVE

The document includes recommendations regarding initial evaluation of thyroid nodules, clinical and ultrasound criteria for fine-needle aspiration biopsy, initial management of thyroid cancer including staging and risk assessment, surgical management, radioiodine remnant ablation, and levothyroxine therapy, short-term and long-term follow-up strategies, and management of recurrent and metastatic disease. The objective of this consensus is to inform clinicians, patients, researchers, and health policy makers about the best strategies (and their limitations) relating to the diagnosis and treatment of differentiated thyroid cancer.

Comparison of treatment efficacy 1 and 2 years after thyroid remnant ablation with 1110 versus 5550 MBq of iodine-131 in patients with intermediate-risk differentiated thyroid cancer

BACKGROUND

Radioiodine ablation may be associated with improved survival in patients with intermediate-risk follicular cell differentiated thyroid cancer (FCDTC). The aim of this study was to compare ablation efficacy of 1110 versus 5500 MBq of iodine-131 (I) in FCDTC patients with intermediate risk.

METHODS

Thirty-nine patients with intermediate-risk FCDTC (T3N0, T1-2N1b and T1-3N1a) were treated with 1110 MBq of I and compared with 43 age-matched and sex-matched patients who received 5550 MBq of I. Patients with invasive histology, extensive lymph node involvement, and preablation thyroglobulin (Tg) of more than 100 ng/ml were excluded from the study. All patients underwent total or near total thyroidectomy with or without lymph node dissection. Response to treatment was evaluated 1 and 2 years after I treatment.

RESULTS

We studied four male and 78 female patients, age range 21-69 years. Preablation Tg level was 12.7±17.8 and 15.8±22.6 ng/ml in patients in the low-dose and high-dose groups, respectively (P=0.48). Anti-Tg antibody level as well as T and N staging were not significantly different in the two groups (P>0.2). One and 2 years after treatment, an excellent response was noted in 19 and 22 patients in the low-dose group and in 16 and 23 patients in the high-dose group, respectively (P>0.3). Using logistic regression analysis, preablation Tg was the only significant factor in the prediction of an incomplete response 2 years after therapy.

CONCLUSION

1110 MBq of I was as effective as 5550 MBq of I in the treatment of FCDTC patients with intermediate risk 1 and 2 years after therapy.

Clinical outcomes of low and intermediate risk differentiated thyroid cancer patients treated with 30mCi for ablation or without radioactive iodine therapy

OBJECTIVE

To retrospectively evaluate the outcomes of patients with low and intermediate risk thyroid carcinoma treated with total thyroidectomy (TT) and who did not undergo radioiodine remnant ablation (RRA) and to compare them to patients receiving low dose of iodine (30 mCi).

SUBJECTS AND METHODS

A total of 189 differentiated thyroid cancer (DTC) patients treated with TT followed by 30mCi for RRA or not, followed in two referral centers in Brazil were analyzed.

RESULTS

From the 189 patients, 68.8% was ATA low-risk, 30.6% intermediate and 0.6% high risk. Eighty-seven patients underwent RRA and 102 did not. The RRA groups tended to be younger and had a higher frequency of extra-thyroidal extension (ETE). RRA did not have and impact on response to initial therapy neither in low (p = 0.24) nor in intermediate risk patients (p = 0.66). It also had no impact on final outcome and most patients had no evidence of disease (NED) at final follow-up. Recurrence/persistence of disease was found in 1.2% of RRA group and 2% in patients treated only with TT (p = 0.59).

CONCLUSIONS

Our study shows that in low and intermediate-risk patients, RRA with 30 mCi seems to have no major advantage over patients who did not undergo RRA regarding response to initial therapy in each risk group and also in long term outcomes.

Low-Dose Radioactive Iodine Ablation Is Sufficient in Patients With Small Papillary Thyroid Cancer Having Minor Extrathyroidal Extension and Central Lymph Node Metastasis (T3 N1a)

PURPOSE

The aim of this study was to evaluate the effectiveness of low-dose radioactive iodine (RAI) ablation in patients with small papillary thyroid cancer (PTC) exhibiting microscopic extrathyroidal extension (mETE) and central lymph node (CLN) metastasis.

METHODS

Among patients who underwent RAI ablation between March 2007 and February 2014, those who had small PTCs (≤2 cm), as well as mETE and CLN metastasis (T3 N1a M0), were enrolled. Response to ablation and long-term outcomes were assessed and compared according to the administered RAI dose. Factors associated with unsuccessful ablation were also determined.

RESULTS

A total of 180 patients were included in the study. Eighty-eight patients had been treated with 1110 MBq (low-dose group) and 92 with 2960 MBq (high-dose group) of RAI. There were no significant differences in the responses to ablation (P = 0.810) and long-term outcomes (P = 0.663) between both groups. Among all patients enrolled, 13 did not achieve successful ablation at long-term follow-up. Logistic regression found that a high ratio of metastatic nodes was a significant factor for predicting unsuccessful ablation.

CONCLUSIONS

Low-dose RAI ablation did not produce significantly different responses or long-term outcomes in patients with small PTCs exhibiting mETE and CLN metastasis. These findings suggest that low-dose ablation may be sufficient in this specific group of intermediate-risk patients, although careful selection is required for patients with a high ratio of metastatic nodes.

Selected Controversies of Radioiodine Imaging and Therapy in Differentiated Thyroid Cancer

This article discusses the more controversial areas of the management of differentiated thyroid cancer, namely, the utility of pretherapy staging radioiodine scans; the prescribed activity for iodine-131 remnant ablation, adjuvant treatment, and distant metastases; preparation with thyroid hormone withdrawal versus recombinant human thyroid-stimulating hormone; and the classification of radioiodine refractory differentiated thyroid cancer. The author reviews various aspects of the controversies, such as the recommendations of the 2015 guidelines of the American Thyroid Association, arguments for and against the various controversies, and selected references.

Radioiodine Ablation following Thyroidectomy for Differentiated Thyroid Cancer: Literature Review of Utility, Dose, and Toxicity

Management recommendations for differentiated thyroid cancer are evolving. Total thyroidectomy is the backbone of curative-intent therapy, with radioiodine ablation (RAI) of the thyroid remnant routinely performed, in order to facilitate serologic surveillance and reduce recurrence risk. Several single-institution series have identified patient subsets for whom recurrence risk is sufficiently low that RAI may not be indicated. Further, the appropriate dose of RAI specific to variable clinicopathologic presentations remains poorly defined. While recent randomized trials demonstrated equivalent thyroid remnant ablation rates between low- and high-dose RAI, long-term oncologic endpoints remain unreported. While RAI may be employed to facilitate surveillance following total thyroidectomy, cancer recurrence risk reduction is not demonstrated in favorable-risk patients with tumor size ≤1 cm without high-risk pathologic features. When RAI is indicated, in patients without macroscopic residual disease or metastasis, the evidence suggests that the rate of successful remnant ablation following total thyroidectomy is equivalent between doses of 30-50 mCi and doses ≥100 mCi, with fewer acute side effects; however, in the setting of subtotal thyroidectomy or when preablation diagnostic scan uptake is >2%, higher doses are associated with improved ablation rates. Historical series demonstrate conflicting findings of long-term cancer control rates between dose levels; long-term results from modern series have yet to be reported. For high-risk patients, including those with positive surgical margins, gross extrathyroidal extension, lymph node involvement, subtotal thyroidectomy, or >5% uptake, higher-dose RAI therapy appears to provide superior rates of ablation and cancer control.

The role of ablative treatment in differentiated thyroid cancer management

The role of ablative treatment in differentiated thyroid cancer management has been evolving over the years. After its introduction in clinical practice, the use of postsurgical radioiodine treatment was generalized to almost every patient with differentiated thyroid cancer, with the exception of unifocal microcarcinomas. However, in the last decade several studies questioned its benefit in low- and intermediate-risk patients. Areas covered: In this review we discuss the role of postsurgical radioiodine treatment at the present time. Expert commentary: Although there is general consensus about the recommendation for very low-risk (microcarcinomas) and high-risk patients - no indication for routine postoperative radioiodine and clear indication for radioiodine treatment, respectively, the recommendation for low- and intermediate-risk patients is still under debate. The most recent guidelines from the American Thyroid Association make a statement against routine postoperative radioiodine in both low- and intermediate-risk cases, recommending an individualized approach that takes into consideration the risk of disease persistence or recurrence after surgery. We consider that these recommendations are in accordance with the best evidence available today, and we would like to emphasize that radioiodine is generally favored for most intermediate-risk patients, especially in the presence of extensive lymph node disease or older age.

Reappraisal of the indication for radioiodine thyroid ablation in differentiated thyroid cancer patients

Radioactive iodine therapy is administered to patients with differentiated thyroid cancer (DTC) for eradication of thyroid remnant after total thyroidectomy or, in patients with metastatic disease, for curative or palliative treatment. In past years, thyroid remnant ablation was indicated in almost every patient with a diagnosis of DTC. Nowadays, careful revision of patients' outcome has introduced the concept of risk-based selection of patients candidate to thyroid remnant ablation. The present review aims to underline the indications for thyroid remnant ablation and to address methodologies to be employed.

Prediction of radioactive iodine remnant ablation failure in patients with differentiated thyroid cancer: A cohort study of 740 patients

BACKGROUND

The purpose of this study was to detect parameters that could serve as predictors of radioactive iodine (I-131) ablation failure in patients with low-risk and intermediate-risk differentiated thyroid carcinoma (DTC).

METHODS

Our cohort study included 740 patients with DTC who received postoperative I-131 remnant ablation. Anthropometric, biochemical, and pathohistological parameters were analyzed and correlated with ablation outcome using multivariable logistic regression models.

RESULTS

Treatment failure rates were higher in patients <53 years, with N1a classification, and lymph node capsular invasion. In patients with N1a disease, thyroglobulin (Tg) > 2.4 ng/mL predicted treatment failure with 93.8% sensitivity and 52.5% specificity, and in patients with N1b disease, Tg > 14.9 ng/mL with 77.8% sensitivity and 92.9% specificity. I-131 activity was not associated with treatment outcome.

CONCLUSION

Patients < 53 years old, with higher Tg levels, N1a classification, and lymph node capsular invasion have a higher risk of ablation failure. Stimulated Tg is an excellent predictor of treatment failure in patients with N1 disease. © 2016 Wiley Periodicals, Inc. Head Neck 39: 109-115, 2017.

Long-Term Outcomes of Patients with Papillary Thyroid Cancer Undergoing Remnant Ablation with 30 milliCuries Radioiodine

BACKGROUND

The study considered the long-term outcome of patients with papillary thyroid carcinoma treated with 30 mCi radioiodine.

OBJECTIVE

The aims of this study were to define and compare the remission rates of papillary thyroid carcinoma ablated with 30 mCi (131)I prepared by either thyroid hormone withdrawal (THW) or recombinant human thyrotropin (rhTSH; Thyrogen(®)), and to identify variables predictive of a favorable prognosis.

METHOD

An observational study was conducted at an academic medical center and a comparative summary of six studies is presented. Three hundred and seventy patients (THW group, n = 203; rhTSH group, n = 167) were recruited from a prospectively managed registry. The mean follow-up was 9.3 years (range 5.1-15.8 years) in the THW group and 7.1 years (range 5.0-9.7 years) in the rhTSH group. The primary endpoint was the long-term remission rates (no evidence of disease) in the THW group compared with the rhTH group.

RESULTS

The response at 12-18 months after 30 mCi remnant ablation was excellent in 79.3% and 76.0% of patients in the THW group and the rhTSH group, respectively (p > 0.05). The long-term remission rates also did not significantly differ between both groups at 95.6% and 97.0%. Although the surveillance period for the THW group exceeded that of the rhTSH group, no significant difference in recurrence-free survival was discerned by the Kaplan-Meier curves. In a multivariate analysis, an excellent response to therapy at 12-18 months correlated significantly with long-term remission rates in the THW group (p = 0.031, odds ratio [OR] = 2.6 [confidence interval (CI) 1.1-6.0]), the rhTSH group (p = 0.03, OR = 5.3 [CI 1.2-23.8]), and the pooled groups (p = 0.001, OR = 3.43 [CI 1.63-7.2]). The pre-ablation thyroglobulin level significantly correlated with remission rates only in the THW group (p = 0.035, OR = 5.5 [CI 1.1-27.1]).

CONCLUSIONS

The response to remnant ablation with 30 mCi radioiodine is often excellent, and the long-term remission rates can be expected to be high, independent of the method of delivery (i.e., THW or rhTSH).

Intermediate-risk differentiated thyroid carcinoma patients who were surgically ablated do not need adjuvant radioiodine therapy: long-term outcome study

OBJECTIVE

The mute question is whether patients with DTC of intermediate risk of recurrence, second most common presentation, who were surgically ablated in the first place, ever needed adjuvant RAI therapy? This study exclusively evaluated the long-term outcome in intermediate-risk patients with DTC.

DESIGN

Two-arm retrospective cohort study conducted between years 1991 and 2012.

SETTING

Institutional practice.

PATIENTS

Intermediate-risk DTC patients, with pathologically proven T1/2 N1 M0, T3 with/without N1 M0 disease, with a minimum follow-up of 12 months, were included. Of 254 patients who fulfilled the inclusion/exclusion criteria, 125 patients were surgically ablated (Gr-I) and 129 patients had significant remnant and/nodal disease (Gr-II). No radioiodine in Gr-I and adjuvant RAI therapy was administered in Gr-II patients.

MEASUREMENTS

Baseline characteristics were compared and overall survival, event-free survival, disease-free survival/overall remission rates and recurrence rates were calculated for both the groups.

RESULTS

All baseline patient characteristics were comparable except 24-h RAIU between two groups. Depending on adjuvant radioiodine therapy outcome, Gr-II patients were subclassified as Gr-IIa (ablated) and Gr-IIb (not ablated). With a median follow-up duration of 10·3 years (range: 1-21 years), 12/125 (9·6%) patients had disease recurrence and 10 (8%) showed persistent disease in Gr-I. In Gr-IIa, 6/102 (5·9%) patients recurred but only one of them was successfully ablated with (131) I, and 5 (4·9%) had persistent disease. However, in Gr-IIb, 27 patients who failed first-dose adjuvant RAI therapy, 8/27 (29·6%) showed persistent disease (P = 0·000). Overall survival was 100%; however, disease-free survival rates were 92% and 90%, in Gr-I and Gr-II, respectively.

CONCLUSION

Intermediate-risk surgically ablated patients do not need adjuvant RAI therapy and patients who failed to achieve ablation with first dose of (131) I may be dynamically risk stratified as high-risk category and managed aggressively.

Recommendations for post-surgical thyroid ablation in differentiated thyroid cancer: a 2015 position statement of the Italian Society of Endocrinology

Post-surgical ablation of thyroid remnant with radioactive iodine (RAI) in differentiated thyroid cancer (DTC) is aimed to destroy any thyroid remnant in the thyroid bed (remnant ablation) and any microscopic foci of cancer cells eventually present within the thyroid remnant (adjuvant therapy). The present text is an attempt to offer practice guidelines for the indication of thyroid ablation and the preparation of DTC patients considering the latest achievement in the field and the changing epidemiology of DTC observed in the last 10 years.

METHODOLOGY

The executive committee of the Italian Society of Endocrinology appointed a task force of thyroid cancer expert including Nuclear Medicine Physicians and Endocrinologists to provide a consensus on the post-surgical ablation in thyroid cancer patients. The task force had no conflict of interest and had no commercial support. A number of specific topics were selected and the members selected relevant papers by searching in the Pubmed for articles published from 2000 to January 2015. Selected studies were categorized by level of evidence, and the recommendations were graded according to the level of evidence as high (A), moderate (B), or low (C).

Indications for radioiodine administration in follicular-derived thyroid cancer

Indications for radioiodine administration after thyroid cancer surgery have shifted in recent years toward personalized management, adapted to the individual risk of tumor progression. The most recent guidelines and studies favor de-escalation in indications for administration, dosage and means of preparation with exogenous recombinant TSH stimulation as treatment of choice. Radioiodine administration has 3 possible objectives: • ablation of normal thyroid tissue remnants in patients with low risk of progression, using low radioiodine activity levels, with the advantage of completing disease staging on whole-body scintigraphy performed after administration of the radioiodine capsule, and of facilitating follow-up by thyroglobulin assay; • adjuvant treatment for suspected microscopic metastases in patients with intermediate or high risk of progression, using higher activity levels, with the theoretic aim of limiting recurrence and mortality; • curative treatment in high-risk patients with proven metastases, using exclusively high activity levels, with a view to improving specific survival. In future, indications for ablation and/or activity prescription may be governed by an algorithm incorporating individual baseline progression risk (essentially founded of pTNM staging) and postoperative data such as thyroglobulin level and neck ultrasound results.